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Merge pull request #1 from pantonshire/capped-string

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CappedString improvements
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pantonshire 3 years ago committed by GitHub
parent 82034e14d0 cad45f5bce
commit 352c01f613
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2 changed files with 553 additions and 63 deletions
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src/strings/capped.rs
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@ -20,12 +20,24 @@ use alloc::{
#[cfg(feature = "std")]
use std::borrow::Cow;
#[derive(Debug)]
pub struct CapacityError;
impl fmt::Display for CapacityError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "`CappedString` capacity exceeded")
}
}
#[cfg(feature = "std")]
impl std::error::Error for CapacityError {}
/// A string type which stores at most `N` bytes of string data. The string data is stored inline
/// rather than using a heap allocation.
///
/// ```
/// # use libshire::strings::CappedString;
/// # fn main() -> Result<(), libshire::strings::capped::Error> {
/// # fn main() -> Result<(), libshire::strings::capped::CapacityError> {
/// let s = CappedString::<16>::new("hello world")?;
/// assert_eq!(&*s, "hello world");
/// # Ok(())
@ -50,8 +62,8 @@ impl<const N: usize> CappedString<N> {
/// Creates a new `CappedString` from a given byte buffer and length.
///
/// # Safety
///
/// The first `len` bytes of `buf` (i.e. `buf[..len]`) must be initialised and valid UTF-8.
/// The first `len` bytes of `buf` (i.e. `buf[..len]`) must be initialised and valid UTF-8.
/// `len` must be less than or equal to `N`.
#[inline]
#[must_use]
pub const unsafe fn from_raw_parts(buf: [MaybeUninit<u8>; N], len: u8) -> Self {
@ -60,10 +72,76 @@ impl<const N: usize> CappedString<N> {
#[inline]
#[must_use]
pub fn into_raw_parts(self) -> ([MaybeUninit<u8>; N], u8) {
pub const fn into_raw_parts(self) -> ([MaybeUninit<u8>; N], u8) {
(self.buf, self.len)
}
/// # Safety
/// `src` must point to `len` bytes of valid, UTF-8 string data. `len` must be less than or
/// equal to `N`.
#[inline]
unsafe fn from_raw_ptr(src: *const u8, len: u8) -> Self {
// `u8` has the same memory layout as `MaybeUninit<u8>`, so this cast is valid.
let src = src as *const MaybeUninit<u8>;
// SAFETY:
// `MaybeUninit::uninit()` is a valid value for `[MaybeUninit<u8>; N]`, since each element
// of the array is allowed to be uninitialised.
let mut buf = unsafe { MaybeUninit::<[MaybeUninit<u8>; N]>::uninit().assume_init() };
// SAFETY:
// The caller is responsible for ensuring that `src` points to a valid string, which means
// that it must not overlap with the new local variable `buf`. The caller is responsible
// for ensuring that `src` is valid for reads of `len` bytes. The caller is responsible for
// ensuring that `len <= N`, so `buf` is valid for writes of `len` bytes. `src` and `buf`
// are both trivially properly aligned, since they both have an alignment of 1.
unsafe { ptr::copy_nonoverlapping(src, buf.as_mut_ptr(), usize::from(len)); }
// SAFETY:
// The caller is responsible for ensuring that `src` points to `len` bytes of valid UTF-8
// data. `src` is copied into the start of `buf`, so the first `len` bytes of `buf` are
// valid UTF-8. The caller is responsible for ensuring that `len <= N`.
unsafe { Self::from_raw_parts(buf, len) }
}
/// # Safety
/// `self.len` must be less than `N`, so that there is space in the buffer to append the byte.
/// The byte must be a valid UTF-8 codepoint; it must be in the range `0..=127`.
#[inline]
unsafe fn append_byte(&mut self, byte: u8) {
// SAFETY:
// The caller is responsible for ensuring that `self.len < N`.
let dst = unsafe { self.buf.get_unchecked_mut(usize::from(self.len)) };
*dst = MaybeUninit::new(byte);
self.len += 1;
}
/// # Safety
/// `src` must point to `len` bytes of valid UTF-8 string data. `len` must be less than or equal
/// to `N - self.len`.
#[inline]
unsafe fn append_bytes(&mut self, src: *const u8, len: u8) {
// `u8` has the same memory layout as `MaybeUninit<u8>`, so this cast is valid.
let src = src as *const MaybeUninit<u8>;
// SAFETY:
// `self.len <= N` is an invariant of `CappedString`, so `self.len..` is a valid range over
// `self.buf`.
let dst = unsafe { self.buf.get_unchecked_mut(usize::from(self.len)..) };
// SAFETY:
// The caller is responsible for ensuring that `src` points to a valid string, which means
// that it cannot overlap with the new local variable `buf`. The caller is responsible for
// ensuring that `src` is valid for reads of `len` bytes. The caller is responsible for
// ensuring that `len <= N - self.len`, so the destination `dst = self.buf[self.len..]` is
// valid for writes of `len` bytes. `src` and `dst` are both trivially properly aligned,
// since they both have an alignment of 1.
unsafe { ptr::copy_nonoverlapping(src, dst.as_mut_ptr(), usize::from(len)); }
self.len += len;
}
/// Returns a new empty `CappedString`.
///
/// ```
@ -90,53 +168,224 @@ impl<const N: usize> CappedString<N> {
/// Returns a new `CappedString` containing the given string data. The string data will be
/// stored inline; no heap allocation is used. An error will be returned if the length of the
/// provided string exceeds the `CappedString`'s maximum length, `N`.
///
/// If you would like a version which never returns an error, see [`Self::new_truncating`].
///
/// ```
/// # use libshire::strings::CappedString;
/// # fn main() -> Result<(), libshire::strings::capped::Error> {
/// # fn main() -> Result<(), libshire::strings::capped::CapacityError> {
/// let s = CappedString::<16>::new("hello world")?;
/// assert_eq!(&*s, "hello world");
/// # Ok(())
/// # }
/// ```
#[inline]
pub fn new<S>(s: &S) -> Result<Self, Error>
pub fn new<S>(src: &S) -> Result<Self, CapacityError>
where
S: AsRef<str> + ?Sized,
{
// Convert the string to a byte slice, which is guaranteed to be valid UTF-8 since this is
// an invariant of `str`.
let src = <S as AsRef<str>>::as_ref(s).as_bytes();
// If the length of the string is greater than `Self::MAX_LEN`, it will not fit in the
// buffer so return `None`.
let len = u8::try_from(src.len())
.ok()
.and_then(|len| (len <= Self::MAX_LEN).then_some(len))
.ok_or(Error {
max_len: N,
actual_len: src.len(),
})?;
let src = <S as AsRef<str>>::as_ref(src);
// If the length of the `src` string does not fit into a `u8` or is greater than
// `Self::MAX_LEN`, we can't fit it into the new `CappedString` so return an error.
let len = match u8::try_from(src.len()) {
Ok(len) if len <= Self::MAX_LEN => len,
_ => return Err(CapacityError),
};
// SAFETY:
// `MaybeUninit::uninit()` is a valid value for `[MaybeUninit<u8>; N]`, since each element
// of the array is allowed to be uninitialised.
let mut buf = unsafe { MaybeUninit::<[MaybeUninit<u8>; N]>::uninit().assume_init() };
// `src.as_ptr()` points to `len` bytes of valid UTF-8 string data since `src` is a `&str`
// and `len` is its length. `len` is less than or equal to `Self::MAX_LEN`, which is equal
// to `N`.
unsafe { Ok(Self::from_raw_ptr(src.as_ptr(), len)) }
}
/// Returns a new `CappedString` containing the given string data. The string data will be
/// stored inline; no heap allocation is used. If the length of the provided string exceeds the
/// `CappedString`'s maximum length, `N`, it will be truncated to fit.
///
/// If you would like a version which returns an error rather than truncating the string, see
/// [`Self::new`].
///
/// ```
/// # use libshire::strings::CappedString;
/// let s1 = CappedString::<15>::new_truncating("こんにちは");
/// assert_eq!(&*s1, "こんにちは");
///
/// let s2 = CappedString::<10>::new_truncating("こんにちは");
/// assert_eq!(&*s2, "こんに");
/// ```
#[inline]
#[must_use]
pub fn new_truncating<S>(src: &S) -> Self
where
S: AsRef<str> + ?Sized,
{
let src = <S as AsRef<str>>::as_ref(src);
let src_ptr = src.as_ptr() as *const MaybeUninit<u8>;
let (src, len) = truncate_str(src, Self::MAX_LEN);
// SAFETY:
// The source and destination to not overlap, since `buf` is a new local variable which is
// completely separate from the provided source string `s`. The source is valid for reads of
// `len` bytes since `len == src.len()`, and the destination is valid for writes of `len`
// bytes since `len <= N`. The source and destination are both trivially properly aligned,
// since they both have an alignment of 1.
unsafe { ptr::copy_nonoverlapping(src_ptr, buf.as_mut_ptr(), usize::from(len)) }
// It is part of the contract of `truncate_str` that it returns a pointer to a valid UTF-8
// string of length `len`, and that `len` is less than or equal to the provided maximum
// length, which is `Self::MAX_LEN` (which is equal to `N`) in this case.
unsafe { Self::from_raw_ptr(src, len) }
}
/// Appends the given character to the end of this `CappedString`, returning an error if there
/// is insufficient capacity remaining to do so.
///
/// If you do not care whether or not the append succeeds, see [`Self::push_truncating`].
#[inline]
pub fn push(&mut self, c: char) -> Result<(), CapacityError> {
let mut char_buf = [0u8; 4];
let encoded = c.encode_utf8(&mut char_buf);
match encoded.len() {
1 => {
if self.len == Self::MAX_LEN {
return Err(CapacityError);
}
// SAFETY:
// We have checked that `self.len != N` (`Self::MAX_LEN == N`). Since it is an
// invariant of `CappedString` that `self.len <= N`, it must hold that
// `self.len < N`. The first byte of a `str` of length 1 must be a valid UTF-8
// codepoint; it must be in the range `0..=127`, since anything outside this range
// implies the presence of further bytes.
unsafe { self.append_byte(encoded.as_bytes()[0]) }
Ok(())
},
_ => self.push_str(encoded),
}
}
/// Appends the given character to the end of this `CappedString`, failing silently if there is
/// insufficient capacity remaining to do so.
///
/// If you would like to know whether or not the append succeeds, see [`Self::push`].
#[inline]
pub fn push_truncating(&mut self, c: char) {
// Unlike `Self::push_str_truncating`, we can just use `Self::push` and swallow the error
// because a single character will never be partially pushed; it is either pushed or it
// isn't.
self.push(c).ok();
}
/// Appends the given string slice to the end of this `CappedString`, returning an error if
/// there is insufficient capacity remaining to do so.
///
/// If you would like a version which cannot fail, see [`Self::push_str_truncating`].
///
/// ```
/// # use libshire::strings::CappedString;
/// let mut s = CappedString::<8>::empty();
///
/// assert!(s.push_str("hello").is_ok());
/// assert_eq!(&*s, "hello");
///
/// assert!(s.push_str(" world").is_err());
/// assert_eq!(&*s, "hello");
///
/// assert!(s.push_str("!!!").is_ok());
/// assert_eq!(&*s, "hello!!!");
/// ```
#[inline]
pub fn push_str<S>(&mut self, src: &S) -> Result<(), CapacityError>
where
S: AsRef<str> + ?Sized,
{
let src = <S as AsRef<str>>::as_ref(src);
let len = match u8::try_from(src.len()) {
Ok(len) if len <= Self::MAX_LEN - self.len => len,
_ => return Err(CapacityError),
};
// SAFETY:
// `src` is a valid string slice with length `len`. We have checked that
// `len <= N - self.len` holds above (note that `Self::MAX_LEN == N`).
unsafe { self.append_bytes(src.as_ptr(), len); }
Ok(())
}
/// Appends as many of the characters of the given string slice to the end of this
/// `CappedString` as can fit. Any remaining characters will not be added.
///
/// If you would like a version which returns an error if there is not enough capacity remaining
/// to append the entire string slice, see [`Self::push_str`].
///
/// ```
/// # use libshire::strings::CappedString;
/// let mut s = CappedString::<10>::empty();
///
/// s.push_str_truncating("hello");
/// assert_eq!(&*s, "hello");
///
/// s.push_str_truncating(" 世界");
/// assert_eq!(&*s, "hello 世");
///
/// s.push_str_truncating("!!!");
/// assert_eq!(&*s, "hello 世!");
/// ```
#[inline]
pub fn push_str_truncating<S>(&mut self, src: &S)
where
S: AsRef<str> + ?Sized,
{
let remaining_cap = Self::MAX_LEN - self.len;
// Short-circuit if we have no space left to copy into.
if remaining_cap == 0 {
return;
}
let src = <S as AsRef<str>>::as_ref(src);
// Find the longest valid UTF-8 prefix which fits into the remaining space.
let (src, len) = truncate_str(src, remaining_cap);
// SAFETY:
// The first `len` bytes of the buffer are valid UTF-8 because the first `len` bytes of
// the buffer contain data copied from a `&str`, and `&str` is always valid UTF-8.
unsafe { Ok(Self::from_raw_parts(buf, len)) }
// `truncate_str` returns a pointer to `len` bytes of valid UTF-8 string data. The returned
// `len` will always be less than or equal to `remaining_cap`, which is equal to
// `N - self.len` (note that `Self::MAX_LEN == N`).
unsafe { self.append_bytes(src, len); }
}
/// Empties the contents of this `CappedString`.
///
/// ```
/// # use libshire::strings::CappedString;
/// # fn main() -> Result<(), libshire::strings::capped::CapacityError> {
/// let mut s = CappedString::<16>::new("hello")?;
///
/// assert!(!s.is_empty());
/// assert_eq!(&*s, "hello");
///
/// s.clear();
///
/// assert!(s.is_empty());
/// assert_eq!(&*s, "");
/// # Ok(())
/// # }
/// ```
#[inline]
pub fn clear(&mut self) {
// Setting the length to 0 is enough to clear the `CappedString`; we don't need to replace
// any of the old bytes in the buffer, as setting the length to 0 makes all of the old bytes
// inaccessible via safe methods, and means that any future calls to `Self::push` and
// friends will write over the old bytes.
//
// It may be desirable for security-critical code to zero the old buffer to prevent cleared
// data from being exposed via buffer-overflow exploits or similar. However, this should be
// implemented in a separate function so that regular users don't have to pay the cost of
// zeroing the buffer.
self.len = 0;
}
/// Returns a string slice pointing to the underlying string data.
@ -150,15 +399,37 @@ impl<const N: usize> CappedString<N> {
}
/// Returns a mutable string slice pointing to the underlying string data.
///
/// ```
/// # use libshire::strings::CappedString;
/// # fn main() -> Result<(), libshire::strings::capped::CapacityError> {
/// let mut s = CappedString::<16>::new("hello!")?;
/// s.as_str_mut().make_ascii_uppercase();
/// assert_eq!(&*s, "HELLO!");
/// # Ok(())
/// # }
/// ```
#[inline]
#[must_use]
pub fn as_str_mut(&mut self) -> &mut str {
// SAFETY:
// The first `self.len` bytes of `self.buf` (which is returned by `Self::as_bytes_mut`)
// being valid UTF-8 is an invariant of `CappedString`.
// being valid UTF-8 is an invariant of `CappedString`. Since we are returning a `&mut str`
// to the caller, the caller cannot safely use it to mutate this `CappedString`'s buffer in
// a way that violates the UTF-8 property.
unsafe { str::from_utf8_unchecked_mut(self.as_bytes_mut()) }
}
/// Returns a byte slice containing the UTF-8 bytes representing the string.
///
/// ```
/// # use libshire::strings::CappedString;
/// # fn main() -> Result<(), libshire::strings::capped::CapacityError> {
/// let s = CappedString::<16>::new("hello!")?;
/// assert_eq!(s.as_bytes(), &[0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x21]);
/// # Ok(())
/// # }
/// ```
#[inline]
#[must_use]
pub fn as_bytes(&self) -> &[u8] {
@ -176,8 +447,8 @@ impl<const N: usize> CappedString<N> {
}
/// # Safety
/// The caller is responsible for ensuring that the slice is valid UTF-8 when the mutable
/// borrow ends.
/// The slice must be valid UTF-8 when the mutable borrow ends and this `CappedString` is used
/// again.
#[inline]
#[must_use]
pub unsafe fn as_bytes_mut(&mut self) -> &mut [u8] {
@ -194,10 +465,14 @@ impl<const N: usize> CappedString<N> {
unsafe { &mut *(data_slice as *mut [MaybeUninit<u8>] as *mut [u8]) }
}
#[inline]
#[must_use]
pub fn len(&self) -> usize {
usize::from(self.len)
}
#[inline]
#[must_use]
pub fn is_empty(&self) -> bool {
self.len == 0
}
@ -205,10 +480,14 @@ impl<const N: usize> CappedString<N> {
#[cfg(feature = "alloc")]
impl<const N: usize> CappedString<N> {
#[inline]
#[must_use]
pub fn into_boxed_str(self) -> Box<str> {
self.as_str().into()
}
#[inline]
#[must_use]
pub fn into_string(self) -> String {
self.as_str().to_owned()
}
@ -266,7 +545,7 @@ impl<const N: usize> borrow::BorrowMut<str> for CappedString<N> {
}
impl<'a, const N: usize> TryFrom<&'a str> for CappedString<N> {
type Error = Error;
type Error = CapacityError;
#[inline]
fn try_from(s: &'a str) -> Result<Self, Self::Error> {
@ -276,7 +555,7 @@ impl<'a, const N: usize> TryFrom<&'a str> for CappedString<N> {
#[cfg(feature = "alloc")]
impl<const N: usize> TryFrom<String> for CappedString<N> {
type Error = Error;
type Error = CapacityError;
#[inline]
fn try_from(s: String) -> Result<Self, Self::Error> {
@ -286,7 +565,7 @@ impl<const N: usize> TryFrom<String> for CappedString<N> {
#[cfg(feature = "alloc")]
impl<const N: usize> TryFrom<Box<str>> for CappedString<N> {
type Error = Error;
type Error = CapacityError;
#[inline]
fn try_from(s: Box<str>) -> Result<Self, Self::Error> {
@ -296,7 +575,7 @@ impl<const N: usize> TryFrom<Box<str>> for CappedString<N> {
#[cfg(feature = "alloc")]
impl<'a, const N: usize> TryFrom<Cow<'a, str>> for CappedString<N> {
type Error = Error;
type Error = CapacityError;
#[inline]
fn try_from(s: Cow<'a, str>) -> Result<Self, Self::Error> {
@ -351,7 +630,7 @@ impl<const N: usize> Hash for CappedString<N> {
}
impl<const N: usize> str::FromStr for CappedString<N> {
type Err = Error;
type Err = CapacityError;
#[inline]
fn from_str(s: &str) -> Result<Self, Self::Err> {
@ -373,32 +652,243 @@ impl<const N: usize> fmt::Display for CappedString<N> {
}
}
#[derive(Debug)]
pub struct Error {
max_len: usize,
actual_len: usize,
}
impl Error {
pub fn max_len(&self) -> usize {
self.max_len
}
pub fn actual_len(&self) -> usize {
self.actual_len
/// Returns a pointer to the longest prefix of `src` which is valid UTF-8 and whose length is
/// less than or equal to `max_len`, and returns the length of this prefix.
#[inline]
fn truncate_str(src: &str, max_len: u8) -> (*const u8, u8) {
match u8::try_from(src.len()) {
// If the length of the `src` string is less than or equal to `max_len`, there is no need to
// truncate it.
Ok(src_len) if src_len <= max_len => (src.as_ptr(), src_len),
// If the length of `src` is greater than `max_len`, we need to truncate it. Note that
// `u8::try_from` returning an error means that `src.len() > max_len`, since `max_len` is a
// `u8` and `src.len()` is a `usize`.
_ => {
let src = src.as_bytes();
let mut i = max_len;
// Find the rightmost codepoint which starts at an index less than or equal to
// `max_len`. Everything to the left of this will be valid UTF-8 with a length less
// than or equal to `max_len`. We only need to do 3 iterations because codepoints have
// a maximum length of 4 bytes.
for _ in 0..3 {
// The first byte in the string must always be the start of a codepoint.
if i == 0 {
break;
}
// SAFETY:
// `i <= max_len`, since it is never incremented. If this branch is run, then either
// `src.len(): usize` does not fit into a `u8`, in which case it must be greater
// than `max_len: u8`, or it does fit into a `u8` but it is greater than `max_len`.
// Therefore, `src.len() > max_len` must hold. Substitution gives `i < src.len()`,
// so `i` is a valid index into `src`.
let byte = unsafe { *src.get_unchecked(usize::from(i)) };
// If the byte is not of the form 0b10xxxxxx, then it is the start of a codepoint.
if byte & 0xc0 != 0x80 {
break;
}
i -= 1;
}
// `i < src.len()` always holds as discussed above, so the pointer `src.as_ptr()` is
// valid for reads of `i` bytes. `i` is the index of the start of a codepoint, and
// codepoints are contiguous, so the `i` bytes being pointed to must be valid UTF-8.
(src.as_ptr(), i)
},
}
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(
f,
"string of length {} exceeds limit for `CappedString<{}>`",
self.actual_len,
self.max_len
)
#[cfg(test)]
mod tests {
use super::CappedString;
#[test]
fn test_truncate_str() {
use super::truncate_str;
let s1 = "hello";
assert_eq!(truncate_str(s1, 0), (s1.as_ptr(), 0));
assert_eq!(truncate_str(s1, 1), (s1.as_ptr(), 1));
assert_eq!(truncate_str(s1, 5), (s1.as_ptr(), 5));
assert_eq!(truncate_str(s1, 6), (s1.as_ptr(), 5));
let s2 = "こんにちは";
assert_eq!(truncate_str(s2, 0), (s2.as_ptr(), 0));
assert_eq!(truncate_str(s2, 1), (s2.as_ptr(), 0));
assert_eq!(truncate_str(s2, 2), (s2.as_ptr(), 0));
assert_eq!(truncate_str(s2, 3), (s2.as_ptr(), 3));
assert_eq!(truncate_str(s2, 4), (s2.as_ptr(), 3));
assert_eq!(truncate_str(s2, 5), (s2.as_ptr(), 3));
assert_eq!(truncate_str(s2, 6), (s2.as_ptr(), 6));
assert_eq!(truncate_str(s2, 14), (s2.as_ptr(), 12));
assert_eq!(truncate_str(s2, 15), (s2.as_ptr(), 15));
assert_eq!(truncate_str(s2, 16), (s2.as_ptr(), 15));
assert_eq!(truncate_str(s2, 18), (s2.as_ptr(), 15));
let s3 = "🤖 こんにちは, world 🤖";
assert_eq!(truncate_str(s3, 0), (s3.as_ptr(), 0));
assert_eq!(truncate_str(s3, 1), (s3.as_ptr(), 0));
assert_eq!(truncate_str(s3, 2), (s3.as_ptr(), 0));
assert_eq!(truncate_str(s3, 3), (s3.as_ptr(), 0));
assert_eq!(truncate_str(s3, 4), (s3.as_ptr(), 4));
assert_eq!(truncate_str(s3, 5), (s3.as_ptr(), 5));
assert_eq!(truncate_str(s3, 6), (s3.as_ptr(), 5));
assert_eq!(truncate_str(s3, 7), (s3.as_ptr(), 5));
assert_eq!(truncate_str(s3, 8), (s3.as_ptr(), 8));
assert_eq!(truncate_str(s3, 28), (s3.as_ptr(), 28));
assert_eq!(truncate_str(s3, 29), (s3.as_ptr(), 28));
assert_eq!(truncate_str(s3, 30), (s3.as_ptr(), 28));
assert_eq!(truncate_str(s3, 31), (s3.as_ptr(), 28));
assert_eq!(truncate_str(s3, 32), (s3.as_ptr(), 32));
assert_eq!(truncate_str(s3, 33), (s3.as_ptr(), 32));
assert_eq!(truncate_str(s3, 36), (s3.as_ptr(), 32));
let s4 = "a";
assert_eq!(truncate_str(s4, 0), (s4.as_ptr(), 0));
assert_eq!(truncate_str(s4, 1), (s4.as_ptr(), 1));
assert_eq!(truncate_str(s4, 2), (s4.as_ptr(), 1));
assert_eq!(truncate_str(s4, 3), (s4.as_ptr(), 1));
assert_eq!(truncate_str(s4, 4), (s4.as_ptr(), 1));
let s5 = "";
assert_eq!(truncate_str(s5, 0), (s5.as_ptr(), 0));
assert_eq!(truncate_str(s5, 1), (s5.as_ptr(), 0));
assert_eq!(truncate_str(s5, 2), (s5.as_ptr(), 0));
assert_eq!(truncate_str(s5, 3), (s5.as_ptr(), 0));
assert_eq!(truncate_str(s5, 4), (s5.as_ptr(), 0));
let s6 = "На берегу пустынных волн\n\
Стоял он, дум великих полн,\n\
И вдаль глядел. Пред ним широко\n\
Река неслася; бедный чёлн\n\
По ней стремился одиноко.\n\
По мшистым, топким берегам\n\
Чернели избы здесь и там,\n\
Приют убогого чухонца;\n\
И лес, неведомый лучам\n\
В тумане спрятанного солнца,\n\
Кругом шумел.";
assert_eq!(truncate_str(s6, 0), (s6.as_ptr(), 0));
assert_eq!(truncate_str(s6, 1), (s6.as_ptr(), 0));
assert_eq!(truncate_str(s6, 2), (s6.as_ptr(), 2));
assert_eq!(truncate_str(s6, 3), (s6.as_ptr(), 2));
assert_eq!(truncate_str(s6, 4), (s6.as_ptr(), 4));
assert_eq!(truncate_str(s6, 254), (s6.as_ptr(), 253));
assert_eq!(truncate_str(s6, 255), (s6.as_ptr(), 255));
}
#[test]
fn test_new() {
assert_eq!(&*CappedString::<5>::new("").unwrap(), "");
assert_eq!(&*CappedString::<5>::new("a").unwrap(), "a");
assert_eq!(&*CappedString::<5>::new("hello").unwrap(), "hello");
assert_eq!(&*CappedString::<6>::new("hello").unwrap(), "hello");
assert!(CappedString::<5>::new("hello!").is_err());
assert_eq!(&*CappedString::<6>::new("hello!").unwrap(), "hello!");
assert_eq!(&*CappedString::<5>::new("こ").unwrap(), "こ");
assert!(CappedString::<5>::new("こん").is_err());
assert_eq!(&*CappedString::<6>::new("こん").unwrap(), "こん");
assert!(CappedString::<6>::new("こんにちは").is_err());
assert_eq!(&*CappedString::<0>::new("").unwrap(), "");
assert!(CappedString::<0>::new("a").is_err());
}
#[test]
fn test_new_truncating() {
assert_eq!(&*CappedString::<5>::new_truncating(""), "");
assert_eq!(&*CappedString::<5>::new_truncating("a"), "a");
assert_eq!(&*CappedString::<5>::new_truncating("hello"), "hello");
assert_eq!(&*CappedString::<6>::new_truncating("hello"), "hello");
assert_eq!(&*CappedString::<5>::new_truncating("hello!"), "hello");
assert_eq!(&*CappedString::<6>::new_truncating("hello!"), "hello!");
assert_eq!(&*CappedString::<5>::new_truncating("こ"), "こ");
assert_eq!(&*CappedString::<5>::new_truncating("こん"), "こ");
assert_eq!(&*CappedString::<6>::new_truncating("こん"), "こん");
assert_eq!(&*CappedString::<6>::new_truncating("こんにちは"), "こん");
assert_eq!(&*CappedString::<7>::new_truncating("こんにちは"), "こん");
assert_eq!(&*CappedString::<8>::new_truncating("こんにちは"), "こん");
assert_eq!(&*CappedString::<9>::new_truncating("こんにちは"), "こんに");
assert_eq!(&*CappedString::<3>::new_truncating("🤖 hello 🤖"), "");
assert_eq!(&*CappedString::<4>::new_truncating("🤖 hello 🤖"), "🤖");
assert_eq!(&*CappedString::<14>::new_truncating("🤖 hello 🤖"), "🤖 hello ");
assert_eq!(&*CappedString::<15>::new_truncating("🤖 hello 🤖"), "🤖 hello 🤖");
assert_eq!(&*CappedString::<20>::new_truncating("🤖 hello 🤖"), "🤖 hello 🤖");
assert_eq!(&*CappedString::<0>::new_truncating(""), "");
assert_eq!(&*CappedString::<0>::new_truncating("a"), "");
}
#[test]
fn test_push() {
let mut s = CappedString::<6>::empty();
s.push_str("").unwrap();
assert_eq!(&*s, "");
s.push('h').unwrap();
assert_eq!(&*s, "h");
s.push_str("ello").unwrap();
assert_eq!(&*s, "hello");
assert!(s.push_str(", world").is_err());
assert_eq!(&*s, "hello");
}
#[test]
fn test_push_truncating() {
let mut s = CappedString::<6>::empty();
s.push_str_truncating("");
assert_eq!(&*s, "");
s.push_truncating('h');
assert_eq!(&*s, "h");
s.push_str_truncating("ello");
assert_eq!(&*s, "hello");
s.push_str_truncating(", world");
assert_eq!(&*s, "hello,");
s.clear();
s.push_truncating('こ');
assert_eq!(&*s, "こ");
s.push_truncating('ん');
assert_eq!(&*s, "こん");
s.push_truncating('に');
assert_eq!(&*s, "こん");
s.clear();
s.push_truncating('🤖');
assert_eq!(&*s, "🤖");
s.push_truncating('🤖');
assert_eq!(&*s, "🤖");
s.push_str_truncating("!!!");
assert_eq!(&*s, "🤖!!");
s.clear();
s.push_str_truncating("🤖 ");
assert_eq!(&*s, "🤖 ");
s.push_truncating('🤖');
assert_eq!(&*s, "🤖 ");
s.clear();
s.push_str_truncating(" ");
assert_eq!(&*s, " ");
s.push_str_truncating("🤖🤖🤖");
assert_eq!(&*s, " 🤖");
s.push_truncating('!');
assert_eq!(&*s, " 🤖");
s.clear();
s.push_str_truncating(" ");
assert_eq!(&*s, " ");
s.push_truncating('🤖');
assert_eq!(&*s, " ");
s.push_str_truncating("こんにちは");
assert_eq!(&*s, " こ");
}
}
#[cfg(feature = "std")]
impl std::error::Error for Error {}

2
src/strings/mod.rs
Unescape Escape View File

@ -4,6 +4,6 @@ pub mod capped;
pub mod inlining;
pub use fixed::{FixedString, Error as FixedStringError};
pub use capped::{CappedString, Error as CappedStringError};
pub use capped::{CappedString, CapacityError as CappedStringError};
#[cfg(feature = "alloc")]
pub use inlining::{InliningString, InliningString23};

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